Structures,uplift, and magmatism of the Western Myanmar Arc: Constraints to mid-Cretaceous-Paleogene tectonic evolution of the western Myanmar continental margin |
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| Institution: | 1. Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences), Ministry of Education, Wuhan 430074, China;2. Research Institute, China National Offshore Oil Corporation (CNOOC), Beijing 10027, China;3. Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China;1. Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China;2. Central for Excellence in Tibetan Plateau Earth Sciences, Chinese Academy of Sciences, Beijing 100101, China;3. University of Chinese Academy of Sciences, Beijing 100049, China;1. Laboratory of Provenance Studies, Department of Earth and Environmental Sciences, Università di Milano-Bicocca, Piazza della Scienza 4, 20126 Milano, Italy;2. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. State Key Laboratory of Oil and Gas Geology and Exploitation, School of Resource and Environment, Southwest Petroleum University, Chengdu 610500, China;1. Department of Earth Sciences, University of Oxford, South Parks Road, Oxford OX1 3AN, United Kingdom;2. Department of Geology, Chiang Mai University, Thailand;3. Swedish Museum of Natural History, and Nordic Center for Earth Evolution, Box 50007, SE-104 05 Stockholm, Sweden;4. NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham NG12 5GG, United Kingdom;1. Department of Earth Sciences, University of Oxford, Oxford OX1 3AN, United Kingdom;2. Department of Geological Sciences, Chiang Mai University, Thailand;3. PPT Exploration and Production, Vibhavadi-Rangsit Road, soi 11, Bangkok 10900, Thailand;4. Department of Earth Sciences, University of St Andrews, North Street, St Andrews KY16 9AL, United Kingdom;5. Swedish Museum of Natural History, and Nordic Center for Earth Evolution, Box 50007, SE-104 05 Stockholm, Sweden;6. Centre for Exploration Targeting – Curtin Node, Department of Applied Geology, Western Australian School of Mines, Curtin University, Perth, WA 6845, Australia;7. NERC Isotope Geosciences Laboratory, British Geological Survey, Keyworth, Nottingham NG12 5GG, United Kingdom;8. Department of Geology, Mandalay University, Mandalay, Myanmar |
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| Abstract: | Knowledge of Trans-Himalayan tectono-magmatic evolution is critical to understanding the complex pre-collisional history of southern Eurasia active continental margin. It has been proposed that magmatic rocks of the Trans-Himalayan batholith, extending from southern Tibet to Southeast Asia, are now exposed as the Western Myanmar Arc and Central Granite Belt in Myanmar, yet origin, emplacement, and relationships of the two juxtaposed belts remain poorly constrained. In this study, 2D seismic and drilling data for the Western Myanmar Arc, zircon U-Pb age and Hf isotope and whole-rock geochemical data for magmatic rocks from the arc have been applied. Our seismic profiles, borehole stratigraphic sequences and zircon U-Pb data show that a typical arc-basin system was well developed along the western Myanmar continental margin. The magmatic arc has experienced at least three igneous events in the mid-Cretaceous (110–90 Ma), latest Cretaceous-Early Paleocene (69–64.5 Ma) and Eocene (53–38 Ma), as well as three associated uplift processes in the Late Cretaceous, Eocene and Late Oligocene. Whole-rock geochemical characteristics and zircons showing variable but predominately positive εHf(t) values, suggest a significant juvenile mantle source involving a proportion of ancient subducted sediments and juvenile crustal materials for these typical arc-related magmatic rocks. The identification of mid-Cretaceous to Paleogene magmatic rocks having positive εHf(t) values from the Western Myanmar Arc: 1) indicates that the magmatism can be correlated with the Gangdese arc within the Lhasa terrane of the southern Tibetan Plateau; 2) provides evidence for the proximal-derived model that Paleogene sediments in the Central Myanmar Basin were from the Western Myanmar Arc, but were not delivered by the paleo-Yarlung Tsangpo-Irrawaddy river system from the Gangdese arc; and 3) enables a model of eastward subduction of the Neo-Tethyan/Indian oceanic crust to reflect onset of the magmatism at the mid-Cretaceous and a long-existed back-arc extension in western Myanmar. |
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